ML18057A682

Application for Amend to License DPR-20,changing Tech Spec 3.1.7 to Increase Pressurizer Safety Valve Setpoint Tolerence from Plus or Minus 1% to Plus or Minus 3% of Nominal Lift Pressure

ML18057A682
Person / Time
Site:	Palisades
Issue date:	12/28/1990
From:	Slade G CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML18057A683	List: ML18057A682 ML18057A684
References
NUDOCS 9101020365
Download: ML18057A682 (5)

Text

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NllCHlliAN'S PROliRESS Palisades Nuclear Plant: 27780 Blue Star Memorial Highway, Covert, Ml 49043 December 28, 1990 Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 DOCKET 50-255 -LICENSE DPR-20 -PALISADES PLANT -GB Slade General Manager TECHNICAL SPECIFICATION CHANGE REQUEST -PRESSURIZER SAFETY VALVE SETPOlNT Enclosed is a proposed change to Palisades Specification 3.1.7.a that will increase the pressurizer safety valves setpoint tolerance from +/-1% to +/-3% of nominal lift pressure.

An attachment to the enclosure contains a Technical Specifications page marked up to show the proposed change. Proposed new pages typed in proper format including the proposed will be submitted before February 1, 1991. General Manager -CC -Administrator,-

Region III, -usNRC -NRC Resident Inspector

-Palisades 9101020365 901228Wln' ADOCK 05000255 J P PDR ' A CMS ENER5Y COMPANY '-" .!_ C, ; * ,1. .J_ ij 1 -----------

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CONSUMERS POWER COMPANY Docket 50-255 Request for Change to the Technical Specifications License DPR-20 For the reasons hereinafter set forth, it is requested that the Technical Specifications contained in the Provisional Operating License DPR-20, Docket 50-255, issued to Consumers Power Company on October 16, 1972, for the Plant be changed as described in Section I below: I. Changes A. Change Specification 3.1.7.a to as follows: "The reactor shall not be made critical unless all three pressurizer safety valves are operable with their lift settings maintained between 2500 psia and 2580 psia {+/-3%)." B. Change the sixth paragraph of section 3.1.7 Basis to read as follows: "The overpressurization analysis for the loss of load event for Cycle 8c 2> supports the specified secondary safety valve lift pressure tolerance.

The overpressurization analysis for the loss of load event for Cycle 9C 3> supports the specified primary safety valve lift pressure tolerance of +/-3% and accounts for the new steam generators.

The ASME .B&PV Code, 1986 edition, Section WI, Subsection IWV-3500, specifies ANSI/ASME OM-1-1981 requirements which allow the specified tolerances in the lift pressures of the safety valves." C. Add Reference 3 to Page 3-25 as follows: "{3) II. Discussion Advanced .Nuclear Fuels Corporation Report ANF90-078 "Palisades Cycle 9 An-alysis of Standard Re-view Plan Chapter 15 Events", September 25, 1990". Change A increases the valve setpoint tolerance from +/-1% to +/-3%. Change B adds information supporting the increase in setpoint tolerance to the Basis section; and Change C provides a reference which verifies the information added by change B. The existing Technical Specification criteria for safety valve lift set point tolerance

{+/-1 of the as-found value) was derived from ASME Section III, Division 1, NB-75243.

This code, however, applies to original construction .Qnly. Based on discussions with the valve manufacturer and our testing facility, we have determined that the +/-1% acceptance

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criterion imposed on these valves is too restrictive and may promote valve degradation caused by too frequent testing. 2 Throughout the testing of the valves it has been common for at lease one pressurizer safety valve to exceed the +/-1% criterion.

As a result, an additional safety valve is required to be tested. Following the found testing, the valve setpoints are calibrated to less than +/-1% of the nominal setpoint.

Since setpoint adjustments can only be made through trial and error, it is necessary to "pop" the valve several times before the proper setpoint is achieved.

Excessive actuation of the valves may result in poor setpoint repeatability and unpredictable valve performance caused by steam cutting the nozzle and disk or by changes in the valve spring characteristics.

Increasing the "as-found" setpoint tolerance will result in a decrease in the number of test actuation of the valves and should increase re 1 i ability. III. Analysis of No Significant Hazards Consideration Consumers Power Company finds that activities associated with this. change request include no significant hazards; and, accordingly, a no significant hazards determination per 10 CFR 5.92(c) is justified.

The following evaluation supports the conclusion that the proposed change would not: 1. Involve a significant increase in the probability or*conseguences of an accident previously evaluated.

Increasing the setpoint tolerance of the pressurizer safety valves does not significantly affect the probability of an accident because the safety valve function is only required after an accident has occurred.

The consequences of events and accidents which could potentially challenge the pressurizer safety valves (Loss of Load, Loss of Normal Feedwater and Control Rod Ejection) have been reanalyzed

-* ---using the proposed +/-3% setpoint tolerance.

In neither the Loss of Load event nor the Loss of Normal Feedwater event are the Technical Specifications limits exceeded.

The Control Rod-Ejection accident does not challenge the safety valves and, thus, is not affected by the change in setpoint tolerance.

Since Technical criteria remain satisfied for each of the three events, the consequences of an accident previously evaluated are not significantly increased by increasing the pressurizer safety valve setpoint tolerance to +/-3%. 2. Create the possibility of a new or different kind of accident from any accident previously evaluated.

Increasing the setpoint tolerance of the pressurizer safety valves to +/-3% does not affect the plant operations since the safety valves would open only after an event has occurred.

Additionally, changing

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s-afety -valve--set point tolerance from +/-1% to +/-3% wi 11 not have_ a significant effect on the valve mounting on the pressurizer vessel. The results of an analysis of the effects of increased exhaust shows the associated pipe and nozzle stresses meet design requirements.

Since this*change does not affect operations and does not cause associated pipe and nozzle stresses to exceed design criteria, it does not create the possibility of a new or different kind of accident from any accident previously evaluated.

3. Involve a significant reduction in the margin of safety. This change does not involve a significant reduction in the margin of safety because the two margins of safety that could potentially be affected by this change, the MDNBR and PCS pressure are not caused to exceed existing Technical Specifications criteria.

Three events or accidents, Loss of External Load, Loss of Normal Feedwater and Control Rod Ejection were analyzed using the proposed +/-3% setpoint tolerance.

The PCS pressure postulated in the Control Rod Ejection accident remains lower than the valve setpoints..

In the Loss of Load and Loss of Normal Feedwater events, the MDNBR stays _

than or equal to the Technical Specifications limit and the PCS pressure remains below the Technical Specifications maximum pressure limit.

4 IV. Conclusion The Palisades Plant Review Committee has reviewed this Technical Specification Change Request and has determined that this change does not involve an unreviewed safety question.

Further, the change* involves no significant hazards consideration.

This change has been reviewed by the Nuclear Safety Services Department.

A copy of this Technical Specification Change Request has been sent to the State of Michigan official designated to receive such Amendments to the Operating License. CONSUMERS POWER COMPANY To the best of my knowledge, information and belief, the contents of this ::c1 Specific:?

y;:st are truthful and complete.

' Senior Vice President Energy Supply CC Administrator, Region III, USNRC

• NRC Resident Inspector

-Palisades

!f LIL Sworn and subscribed to before me this zg day of 1990. <Jw d